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    <title>Document</title>
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<script>
    // let arr = [100,200,'a',[1,2,3]]
    // let [a,b,c,[d,e,f]] = arr;
    // console.log(a,b,c,f);


    let arr = [100,200,'a',555]
    let [a,b,c,d = 333] = arr;

   //  let a = 200; 变量以声明
   // a = 200 数组中的值不修改
    // arr[0] = 200 ; 数组中的值将修改
    console.log(arr);
</script>